This invention relates generally to a third party system defining a group of users of an online system to the online system without disclosing the membership of the group to the online system.
Online systems, such as social networking systems, allow users to connect to and to communicate with other users of the online system. Users may create profiles on an online system that are tied to their identities and include information about the users, such as interests and demographic information. The users may be individuals or entities such as corporations or charities. Online systems allow users to easily communicate and to share content with other online system users by providing content to an online system for presentation to other users. Content provided to an online system by a user may be declarative information provided by a user, status updates, check-ins to locations, images, photographs, videos, text data, or any other information a user wishes to share with additional users of the online system. An online system may also generate content for presentation to a user, such as content describing actions taken by other users on the online system.
Third party systems also provide content to users. For example, a third party system provides one or more applications to users or provides web pages or other content for access to users. A third party system may identify groups of users who have accessed content provided by the third party or to whom the third party system presents content. Identifying groups of users allows a third party system to customize content provided to different users or to analyze how presentation of content to users affects actions performed by the users.
However, third party systems often maintain limited information about users, which may limit a third party system's ability to select content of interest to users or to evaluate how different users respond to content. Many third party systems exchange information with certain online system, such as social networking systems, subject to privacy settings or other restrictions on content sharing by different users of online systems, allowing a third party system to leverage information associated with users by online systems by providing an online system with user identifying information corresponding to the users. The online system retrieves stored information associated with the user identifying information and provides the retrieved information to the third party system, subject to privacy settings specified by the users. However, conventional methods for a third party system to obtain information associated with a group of users by an online system require the third party system to provide user identifying information associated with each user of the group. While this allows a third party system to leverage information associated with the group of users by the online system, it also allows the online system to reproduce the group, which may allow the online system to provide content to the group of users that competes with content from the third party system.